This invention relates to the testing of the tip-ring polarity of a telephone receptacle.
Modern telephone equipment utilizes the so-called "Modular concept," meaning that each wall-mounted receptacle at a subscriber's location is a module capable of accepting the plug of a telephone which can be disconnected from the module and connected to a module in another room. With certain phones (e.g., "Touch Tone" phones), it is important that the final terminals of each receptacle be connected to the central office with the correct tip-ring (i.e., positive-negative) polarity. Both in new installations and in existing installations which are converted to the modular concept, it is possible that one or more receptacles could be miswired in that the final tip-ring terminals of the receptacle could be reversely wired with respect to tip-ring of the central office.